Papers by Keyword: V-Groove

Abstract: 1200 V / 200 A V-groove trench MOSFET optimized to achieve low power loss, high oxide reliability under a drain bias condition and high avalanche ruggedness is shown in this paper. We revealed a relationship between the lifetime under a high temperature reverse bias condition and the oxide electric field. In accordance with the results of the test, the 1200 V / 200 A trench MOSFET showed an improvement in the tradeoff between the on-resistance and oxide electric field with the presence of current spreading layers. In order to obtain low on-resistance and high avalanche ruggedness at the same time, buried guard ring structures, which made the blocking voltage of the edge termination area higher than that of the active area, was developed. The fabricated MOSFETs demonstrated a low specific on-resistance of 3.1 mΩ cm². A predicted lifetime of 200 years under a high temperature drain bias condition of 1200 V was achieved by the optimized design. A short circuit withstand time of 6 μs and a high avalanche energy of 7.8 J/cm² were shown.

Abstract: A 0.63 mΩcm² / 1170 V property was demonstrated in a 4H-SiC V-groove trench MOSFET with a super junction (SJ) structure. Successful results in SJ-VMOSFETs will inspire research on 600 to 1200 V class devices as their extreme high MOS channel mobility and the SJ structure is promising.

Abstract: We have fabricated Super Junction (SJ) V-groove trench MOSFETs (VMOSFETs), demonstrated a low specific on-resistance (R_onA) of 0.97 mΩcm² and a blocking voltage (V_B) of 820 V. In the first trial, SJ structure in 4H-SiC have proved to be a good combination with MOS interface on (0-33-8) faces which keep high channel mobility in high doping concentration. We designed a protection structure called “upper p-pillar region” and demonstrated that V_B lowering appeared according to its width.

Abstract: This paper presents a study of cutting strategies on the surface generation in single-point diamond turning of micro V-groove patterns on precision roller drums. An aluminium precision roller drum with a diameter 250mm and 100 long was diamond turned with a V-groove pattern. A series of cutting experiments were designed to study the effect of the variation of various cutting parameters and cutting tool paths on the surface quality in diamond turning of the precision roller drum. The parameters under investigation included the depth of cut, number of steps and the depth for each cut when diamond turning V-grooves on the cylindrical surface of a workpiece. The measurement result indicates that the surface quality of V-grooves machined on the precision roller drums is affected by cutting strategies. The optimal cutting strategy for machining a V-groove pattern on a precision drum with 5µm depth was obtained.

Abstract: A breakdown of a conventional trench SiC-MOSFET is caused by oxide breakdown at the bottom of the trench. We have fabricated a novel trench SiC-MOSFET with buried p+ regions and demonstrated the high breakdown voltage of 1700 V and the specific on-resistance of 3.5 mΩcm².

Abstract: Thermal microimprint is a promising technology for polymer microstructure, so it is used to form V-groove on the surface of optical devices. However, it is difficult to control the size accuracy of V-groove because of the elastic recovery of polymer. In order to solve the problem, the influencing factors on the polymer elastic recovery were firstly analyzed in this article. Then, it was proposed that the embossment height of mold should be modified according to the depth of V-groove and the modifier formulas should be constructed based on the theory of polymer viscoelasticity. In the end, the optimal technological parameters of thermal microimprint were obtained through the thermal imprint experiments, and the embossment height of the mold after modification was calculated according to the experimental data, and thus a new mold was produced as to verify the accuracy of the modifier formulas. The results showed that the approach of modification could not only ensure dimension accuracy of V-groove, by keeping the error within 1μm, but also shorten the imprint time, consequently the efficiency of thermal microimprint would be improved.

Abstract: A light emitting diode (LED) light guide bar based on concave V-grooves is investigated by using optical simulation software to control the distribution of illumination angle. The structure parameters of V-groove and the distribution of micro-prism are considered. It is found that the illumination angle of LED light guide bar is most concentrated within ±35 degrees.

Abstract: Micro V-groove cutting of cobalt-free tungsten carbide using two types of V-shaped diamond tools is performed using mist of zinc dialkyl-dithiophosphate (ZnDDP) as lubricant. The two types of tool tested are 1) mono-crystalline diamond and 2) poly-crystalline diamond made of approximately 30 nm-sized diamond crystals. The geometry of the V-groove-cutting process is theoretically investigated and the relationship between V-groove angle, original rake angle, and effective rake angle is clarified. Through the cutting experiments, the effects of diamond types and rake angle on tool-wear characteristics are explained. When rake angle is set at zero degrees, tool chipping frequently occurs for both types of diamond tools even when ZnDDP is supplied. However, when rake angle is set at -30 degrees for poly-crystalline diamond, tool wear is minimized.

Abstract: A ~1.2 meter long trough comprising of variable cross-sections, with the highest ratio of depth to opening width reaching 1.4, is gas-formed at 500°C with superplastic aluminum alloy 5083. It is a challenge to successfully make such an industrial scale part as demonstrated in this paper. Starting as an expanded V-shaped groove, pressurized gas is manipulated to flow into the forming die, and the pressure vs. time profile needs to be calculated. Thus, the flow stress in the deforming material is optimal to maintain desired strain rate correspondingly. Thickness distribution over the formed product is far from uniform. The other even undesired result is that the thinnest region suffers severe cavitation

Abstract: V-grooved quartz substrates are manufactured by glass molding press and the pitch errors of the molded quartz fiber array blocks are statistically investigated. The V-grooved carbon molds of 8 and 16 channels and 250 μm in pitch are machined and then quartz substrates are molded on the V-grooved carbon molds by glass molding press. The pitch errors of X, Y and diagonal axis are measured and then statically analyzed. It is demonstrated that the V-grooved quartz fiber array blocks of 8 and 16 channels and 250 μm in pitch can be manufactured by glass molding technology without significant pitch errors.